1. Field of the Invention
The present invention relates to a method of manufacturing semiconductor devices, and more particularly to a method of manufacturing MOS-type semiconductor devices.
2. Description of the Related Art
In recent years, computers and communications devices use integrated circuits (ICs) comprising a plurality of transistors and resistors to configure electric circuits in many cases. Among such the ICs, those including a high-breakdown voltage element are referred to as power ICs. Of the power ICs, those including a drive circuit integrated with a control circuit can be employed in many applications such as display drivers and vehicle-mounted ICs.
A MOS-type field effect transistor (MOSFET) used in the output of the power IC of this type is generally fabricated on a substrate of semiconductor such as silicon through processes of photolithography, ion implantation, thermal oxidation and film formation as described in JP 8-274313A. There is a demand for processes that require a short time and a small number of steps as long as possible from the viewpoint of the cost. In particular, photolithography requires a series of steps such as resist application, pre-baking, exposing by the exposure device, development, and drying. Accordingly, the heavy use extremely lowers the throughput and causes an increase in cost.